Carpet having a foamed secondary backing engaging a primary backing to which textile fibers are secured commonly is applied to hard floor surfaces, such as concrete, vinyl or vinyl-asbestos, where a secondary backing underlying the primary backing provides the shock absorbent layer needed between the primary backing and the hard surface therebeneath. Usually, the secondary backing is formed from a plastisol composition containing polymers or copolymers of vinyl compounds and is applied onto the primary backing during manufacture of the carpet. Once processed, the carpet usually is convolutely wound into roll form so that during installation, the carpet is unrolled, cut to length and applied to a floor thus avoiding the time consuming process of individually laying a large number of small carpet squares.
However, such installation heretofore has been hindered by the extensive floor surface preparation needed to install this type of carpet. Before unrolling and laying the carpet, an adhesive layer is applied to the underlying floor. When the adhesive has set, which typically can take a number of hours depending on the type of adhesive, the carpet then is applied and secured from shifting relative to the underlying floor by the adhesive layer. However, the drawbacks of this prior art technique are readily apparent. Not only is it time consuming, but it also is inherently untidy and bothersome since workmen often must walk upon the applied adhesive to install the carpet. This increases the risk that adhesive could be tracked onto the upstanding carpet surface.
In addition, it is well known in the trade that plasticizer migration inherent in the vinyl plastisol secondary backing causes the degradation of most adhesives. After a number of years following installation of these carpets having the vinyl plastisol secondary backings, the plasticizer migration has degraded most adhesives so that the tackiness and cohesiveness supplied by the adhesive has been reduced. If the carpet subsequently is peeled off the floor, the degraded adhesive is retained thereon. This is especially critical if the adhesive and carpet originally had been applied to a vinyl-asbestos underlying floor. The adhesive's ability to "lock-in" the asbestos is reduced as the adhesive degrades so that asbestos ultimately migrates out from the floor. Although numerous attempts have been made to find a suitable adhesive which is not adversely affected by plasticizer migration inherent in the secondary backing, tests have shown that most commercially available adhesives degrade when used to secure carpets having secondary backings formed of vinyl plastisol compositions.
Finally, any adhesive applied to an underlying floor prior to the installation of an overlying carpet has a greater affinity for the underlying floor than for the installed carpet. Even if a carpet is removed before plasticizer migration has appreciably degraded the adhesive, upon removal of the carpet, the adhesive residue still remains on the underlying floor.
Some prior art techniques have attempted to solve the affinity problem by applying a pressure sensitive adhesive to the backside of a carpet square so as to retain the adhesive on the carpet square if the carpet is peeled away from the floor. U.S. Pat. No. 3,014,829 is representative of the technique of using carpet squares, commonly referred to as carpet tiles, and discloses a pressure sensitive adhesive applied onto a relatively thick, backing pad or cushion serving as a secondary backing as commonly present on conventional carpet squares or tiles. However, it has been found that these efforts have been limited for several reasons. First, industry custom prefers the quicker and more efficient installation of carpet in the form of roll goods. Second, the degradation encountered by most commercially available adhesives when used on the more common vinyl plastisol secondary backings limits their use.
With the foregoing in mind, it is the primary object of this invention to provide a pressure sensitive carpet and method of installing same wherein the carpet includes a vinyl plastisol secondary backing having a pressure sensitive adhesive layer thereon for releasably securing the carpet to an underlying floor and wherein the pressure sensitive adhesive layer is not adversely affected by the plasticizer migration inherent in the secondary backing.
It is a further object of the invention to provide a pressure sensitive carpet in rolled form and method of installing same wherein the carpet includes a vinyl plastisol secondary backing and a pressure sensitive adhesive layer thereon for releasably securing the carpet to an underlying floor and wherein the pressure sensitive adhesive layer is not adversely affected by plasticizer migration inherent in the secondary backing.